Martina Navratilova, one of tennis’ greatest champions, has been added to the all-star field for Mylan WTT Smash Hits presented by GEICO, the annual charity event co-hosted by Sir Elton John and Billie Jean King.

Navratilova, a 59-time Grand Slam champion in singles, doubles and mixed doubles, was one of the participants in the first Smash Hits event in 1993 and will be making her 10th appearance.

Tickets are currently available for Mylan WTT Smash Hits through www.wttsmashhits.com or ticketmaster.com. Corner reserved seats are $40; premium reserved seats are $75; and courtside seats are $125. For group sales of 10 or more tickets, call 412-924-8270.

This year's event marks the 20th anniversary for Smash Hits, which has raised more than $10.5 million for the Elton John AIDS Foundation (EJAF) and various local AIDS charities since 1993. Mylan WTT Smash Hits will benefit EJAF and the Pittsburgh AIDS Task Force, and will also include a pre-match VIP Reception and Auction hosted by Allegheny Sports Medicine.

Navratilova spent 156 consecutive weeks as the world’s No. 1 singles player and shares the all-time Wimbledon record of 20 titles with WTT co-founder Billie Jean King. During her storied career, the Hall of Famer won 18 Grand Slam singles titles, 31 Grand Slam women's doubles and 10 Grand Slam mixed doubles titles. Navratilova holds 167 singles titles, more than any other player, male or female and 177 doubles titles. She is also one of the most successful WTT players in League history, leading her teams to five championships during her 20 seasons.

Knowles is a former world No. 1 in doubles and has won three Grand Slam men’s doubles titles and one mixed doubles crown. He has been a WTT standout during his 11 seasons with the Sacramento Capitals, earning Male MVP honors three times and leading the Caps to two of their six Championship titles. In April 2010, he became only the fifth player in ATP history to record 700 doubles wins.

Gambill reached career-high rankings of No. 14 in singles and No. 23 in doubles during his ATP Tour career, capturing three singles titles and five doubles crowns. Gambill has played eight seasons of WTT, his last five as a member of the Boston Lobsters. He currently coaches former Lobsters teammate Coco Vandeweghe on the WTA Tour.

Captained by King and John, the players will form two teams and play five sets of World TeamTennis (WTT) – one set each of men’s and women’s singles, doubles, and mixed doubles. The music legend is expected to participate in a celebrity doubles match to open the event.

Tickets for the VIP Reception and Auction are sold out. John, King and all players will participate in the pre-match live auction, which will include an Elton John signed piano bench and King’s Wimbledon tickets among other items.

VIP RECEPTION:SOLD OUT. $500. Special VIP tickets packages, including VIP courtside seating and admission to the Mylan Smash Hits VIP Reception and Auction presented by Allegheny Sports Medicine. John, King and all players will participate in the pre-match live auction.